Forensic verification utilizing forensic markings inside halftones

Abstract

A forensic verification system extracts a print signature via a print signature extractor from an interior of a halftone contained in an image. The system utilizes a comparator to compare the print signature to a reference signature stored in a registry to determine differences between the print signature and the reference signature. The system utilizes a forensic analyzer to perform a forensic analysis on the signatures based on the comparison to authenticate the image.

The invention claimed is: 
     
       1. A non-transitory computer readable medium comprising computer executable instructions that when executed cause at least one processor to:
 extract an interior of a halftone of an image of printed media, wherein at least a portion of the interior of the halftone is encoded with a print signature; 
 access a reference signature stored in a registry, wherein the reference signature includes encoded payload information, wherein the halftone is encoded with a payload to form a mapping between the print signature and the payload information; and 
 verify that the printed media is authentic based on a comparison of the print signature and the payload information. 
 
     
     
       2. The non-transitory computer readable medium of  claim 1 , and further comprising computer executable instructions that when executed cause the at least one processor to:
 employ the payload information to index the print signature. 
 
     
     
       3. The non-transitory computer readable medium of  claim 1 , and further comprising computer executable instructions that when executed cause the at least one processor to:
 encode the halftone with the payload information to forma stegatone. 
 
     
     
       4. The non-transitory computer readable medium of  claim 3 , wherein the halftone is encoded with a unique payload to form a one-to-one mapping between the print signature and the payload information. 
     
     
       5. The non-transitory computer readable medium of  claim 3 , wherein the halftone is encoded with a common payload to form a many-to-one mapping between the print signature and the payload information. 
     
     
       6. The non-transitory computer readable medium of  claim 1 , and further comprising computer executable instructions that when executed cause the at least one processor to:
 preprocess the halftone via a bandpass filter to mitigate low and high frequencies within a captured image. 
 
     
     
       7. The non-transitory computer readable medium of  claim 1 , and further comprising computer executable instructions that when executed cause the at least one processor to:
 preprocess the halftone via a difference analyzer that subtracts an image from n aligned captured hardcopy to produce a difference signal image. 
 
     
     
       8. The non-transitory computer readable medium of  claim 1 , and further comprising computer executable instructions that when executed cause the at least one processor to:
 process the halftone via a subdivide area processor that uses an equi-spaced grid to segment the halftone into smaller processing portions. 
 
     
     
       9. The non transitory computer readable medium of  claim 8 , and further comprising computer executable instructions that when executed cause the at least one processor to:
 process the halftone according to concentric regions of an image. 
 
     
     
       10. The non-transitory computer readable medium of  claim 8 , and further comprising computer executable instructions that when executed cause the at least one processor to:
 produce a print signature with an area code generator based on output from the subdivide area processor. 
 
     
     
       11. The non-transitory computer readable medium of  claim 10 , and further comprising computer executable instructions that when executed cause the at least one processor to:
 determine a normalized variance for each processing portion generated by the subdivide area processor. 
 
     
     
       12. A method, comprising:
 recovering a print signature from an interior of a halftone of a captured, image of printed media, wherein the halftone is encoded with the print signature; 
 comparing the print signature to payload information encoded in a reference signature stored in a registry, wherein the halftone is encoded with a payload to form a mapping between the print signature and the payload information; and 
 verifying that the printed media is authentic based on the comparison. 
 
     
     
       13. The method of  claim 12 , and further comprising:
 performing bandpass filtering or digital subtraction on a stegatone formed by encoding the halftone with the payload information; and 
 subdividing the stegatone. 
 
     
     
       14. The method of  claim 12 , and further comprising:
 indexing the print signature using the payload information. 
 
     
     
       15. A system comprising:
 a memory for storing computer executable instructions; and 
 a processing unit for accessing the memory and executing the computer executable instructions, the computer executable instructions comprising: 
 a preprocessor to generate a filtered signal or a difference signal from a captured image of printed media; 
 a subdivide area processor to segment the filtered signal or the difference signal in preparation of further image processing of the captured image of printed media; 
 an area code generator to process segmented output from the subdivide area processor and to recover a print signature from an interior of a halftone that is encoded with payload information; and 
 a verification system to authenticate the printed media by comparing the recovered print signature with a reference signature stored in a print signature registry, wherein the reference signature includes payload information that is used to index the print signature, wherein the halftone is encoded with one of a unique payload to form a one-to-one mapping between the print signature and the payload information or a common payload to form a many-to-one mapping between the print signature and the payload information. 
 
     
     
       16. The method of  claim 12 , wherein the halftone is encoded with a unique payload to form a one-to-one mapping between the print signature and the payload information. 
     
     
       17. The method of  claim 12 , wherein the halftone is encoded with a common payload to form a many-to-one mapping between the print signature and the payload information.